Patent US4773966A successfully refreshed from Google Patents.
US4773966A
Expired / Lapsed
US
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Oxidative degradation of lignin with inorganic metal complexes
Assignee: University of Minnesota System
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Filing: 1986-09-29
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Granted: 1988-09-27
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Expires: 2006-09-29
Abstract
Abstract A method is disclosed to degrade lignin comprising reacting the lignin in a liquid medium under aerobic conditions with an amount of persulfate anion and a transition metal cation effective to catalyze the oxidative degradation of the lignin.
Inventors
- 👤 Van-Ba Huynh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:30
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/16; D21C3/00; D21C3/006
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
47 words
A method to degrade lignin comprising reacting the lignin in a liquid medium under aerobic conditions with an amount of S 2 O 8 -2 and a transition metal ion effective to catalyze the oxidative degradation of the lignin, without the substantial formation of lignin condensation products.
Claim 2
Independent Claim
47 words
A method to degrade lignin comprising reacting the lignin in a liquid medium under aerobic conditions with an amount of S 2 O 8 -2 and a transition metal ion effective to catalyze the oxidative degradation of the lignin, without the substantial formation of lignin condensation products.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the medium comprises a major proportion of water.
Claim 4
Dependent Claim
18 words
The method of claim 1 wherein the pH of the aqueous medium is no higher than about 7.5.
Claim 5
Dependent Claim
15 words
The method of claim 2 wherein the pH of the aqueous medium is about 2-7.5.
Claim 6
Dependent Claim
19 words
The method of claim 1 wherein the aqueous medium comprises an alkali metal persulfate, ammonium persulfate or mixtures thereof.
Claim 7
Dependent Claim
34 words
The method of claim 1 wherein the metal ion is selected from the group consisting of Cu +2 , Co +2 , Ag +1 , Fe +2 , Mn +2 and Ni +2 .
Claim 8
Dependent Claim
13 words
The method of claim 6 wherein the metal ion is Cu +2 .
Claim 9
Dependent Claim
15 words
The method of claim 1 wherein the reaction is carried out at about 50°-100° C.
Claim 10
Dependent Claim
13 words
The method of claim 1 wherein the lignin is present in plant fiber.
Claim 11
Dependent Claim
12 words
The method of claim 1 wherein the lignin is present in pulp.
Claim 12
Independent Claim
47 words
A method to bleach wood pulp comprising delignifying the wood pulp by reacting the pulp in a liquid medium under aerobic conditions with an amount of S 2 O 8 -2 and a transition metal ion effective to catalyze the oxidative degradation of lignin in the pulp.
Claim 13
Independent Claim
47 words
A method to bleach wood pulp comprising delignifying the wood pulp by reacting the pulp in a liquid medium under aerobic conditions with an amount of S 2 O 8 -2 and a transition metal ion effective to catalyze the oxidative degradation of lignin in the pulp.
Claim 14
Dependent Claim
14 words
The method of claim 11 wherein the medium comprises a major proportion of water.
Claim 15
Dependent Claim
18 words
The method of claim 11 wherein the pH of the aqueous medium is no higher than about 7.5.
Claim 16
Dependent Claim
15 words
The method of claim 12 wherein the pH of the aqueous medium is about 2-7.5.
Claim 17
Dependent Claim
19 words
The method of claim 11 wherein the aqueous medium comprises an alkali metal persulfate, ammonium persulfate or mixtures thereof.
Claim 18
Dependent Claim
34 words
The method of claim 11 wherein the metal ion is selected from the group consisting of Cu +2 , Co +2 , Ag +1 , Fe +2 , Mn +2 and Ni +2 .
Claim 19
Dependent Claim
13 words
The method of claim 16 wherein the metal ion is Cu +2 .
Claim 20
Dependent Claim
15 words
The method of claim 11 wherein the reaction is carried out at about 50°-100° C.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-27 | 1992-03-28 | 1992-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-27 | 1996-03-28 | 1996-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-27 | 2000-03-28 | 2000-09-27 | $7700.00 | Window Closed / Lapsed |